ALMA Observations of Complex Organic Molecules in the Disk around the Outbursting Protostar V883 Ori

Yoshihide Yamato  (The University of Tokyo)

Characterizing the chemistry of complex organic molecules (COMs) in star-forming regions is crucial for understanding the chemical evolution at the epoch of star and planet formation. While interferometric observations with ALMA have ubiquitously detected COMs in the warm inner envelopes around protostars, in typical circumstellar disks COMs are frozen out due to the colder nature (<100 K) and thus hidden from view. The disk around the FU Ori type outbursting protostar V883 Ori, where COMs have sublimated due to the temporarily warm (>100 K) conditions, provides a unique opportunity to observe thermally sublimated COMs in the disk environment. In this talk I will present ALMA Band 3 observations of COMs in the V883 Ori disk. These observations detected ten oxygen-bearing COMs including 13C isotopologues. The radial distributions of the COM emission exhibit a common inner emission cavity, suggesting the presence of accretion heating in the disk midplane that hide the COM emission from the disk surface. We found systematically higher abundance ratios of COMs compared to those in the low-mass protostar IRAS 16293-2422 and low 12C/13C ratios (~20-30) of several COMs. This suggests that COMs efficiently (re-)form on the warm dust grain surfaces in the V883 Ori disk, which may indicate the possible chemical reprocessing of COMs in the disk phase.